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Watershed and Stream Network Delineation Including Geomorphology

Watershed and Stream Network Delineation Including Geomorphology. David G. Tarboton dtarb@cc.usu.edu. http://www.engineering.usu.edu/dtarb. Overview. Review of flow direction, accumulation and watershed delineation Topographic texture and drainage density

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Watershed and Stream Network Delineation Including Geomorphology

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  1. Watershed and Stream Network Delineation Including Geomorphology David G. Tarboton dtarb@cc.usu.edu http://www.engineering.usu.edu/dtarb

  2. Overview • Review of flow direction, accumulation and watershed delineation • Topographic texture and drainage density • Channel network geomorphology and Hortons Laws • Stream drop test to objectively oelect channel delineation threshold • Curvature and slope based methods to represent variable drainage density • The D approach • TOPMODEL • Specialized grid accumulation functions • TauDEM software

  3. Elevation Surface — the ground surface elevation at each point Digital Elevation Grid — a grid of cells (square or rectangular) in some coordinate system having land surface elevation as the value stored in each cell.

  4. 67 56 49 52 48 37 58 55 22 Direction of Steepest Descent 30 30 67 56 49 52 48 37 58 55 22 Slope:

  5. 32 64 128 16 1 8 4 2 Eight Direction Pour Point Model

  6. Grid Network

  7. Contributing Area Grid 1 1 1 1 1 1 1 1 1 1 1 4 3 3 1 4 3 1 1 3 1 1 1 1 1 12 1 2 1 12 1 1 1 2 16 1 1 2 1 16 2 1 3 6 25 3 6 1 2 25 TauDEM convention includes the area of the grid cell itself.

  8. 1 1 1 1 1 1 4 3 3 1 1 2 1 1 12 1 1 1 2 16 2 1 3 6 25 Contributing Area > 10 Cell Threshold

  9. Watershed Draining to This Outlet

  10. 100 grid cell constant support area threshold stream delineation

  11. 200 grid cell constant support area based stream delineation

  12. AREA 2 3 AREA 1 12 How to decide on support area threshold ? Why is it important?

  13. Hydrologic processes are different on hillslopes and in channels. It is important to recognize this and account for this in models. Drainage area can be concentrated or dispersed (specific catchment area) representing concentrated or dispersed flow.

  14. Delineation of Channel Networks and Subwatersheds 500 cell theshold 1000 cell theshold

  15. Examples of differently textured topography Badlands in Death Valley.from Easterbrook, 1993, p 140. Coos Bay, Oregon Coast Range. from W. E. Dietrich

  16. Logged Pacific Redwood Forest near Humboldt, California

  17. Canyon Creek, Trinity Alps, Northern California. Photo D K Hagans

  18. Gently Sloping Convex Landscape From W. E. Dietrich

  19. Mancos Shale badlands, Utah. From Howard, 1994.

  20. Same scale, 20 m contour interval Driftwood, PA Sunland, CA Topographic Texture and Drainage Density

  21. “landscape dissection into distinct valleys is limited by a threshold of channelization that sets a finite scale to the landscape.” (Montgomery and Dietrich, 1992, Science, vol. 255 p. 826.) Lets look at some geomorphology. • Drainage Density • Horton’s Laws • Slope – Area scaling • Stream Drops Suggestion:One contributing area threshold does not fit all watersheds.

  22. Drainage Density • Dd = L/A • Hillslope length  1/2Dd B B Hillslope length = B A = 2B L Dd = L/A = 1/2B  B= 1/2Dd L

  23. Drainage Density for Different Support Area Thresholds EPA Reach Files 100 grid cell threshold 1000 grid cell threshold

  24. Drainage Density Versus Contributing Area Threshold

  25. Hortons Laws: Strahler system for stream ordering 1 3 1 2 1 2 1 1 1 1 1 2 2 1 1 1 1 1 1

  26. Bifurcation Ratio

  27. Area Ratio

  28. Length Ratio

  29. Slope Ratio

  30. Slope-Area scaling Data from Reynolds Creek 30 m DEM, 50 grid cell threshold, points, individual links, big dots, bins of size 100

  31. Constant Stream Drops Law Broscoe, A. J., (1959), "Quantitative analysis of longitudinal stream profiles of small watersheds," Office of Naval Research, Project NR 389-042, Technical Report No. 18, Department of Geology, Columbia University, New York.

  32. Nodes Links Single Stream Note that a “Strahler stream” comprises a sequence of links (reaches or segments) of the same order Stream DropElevation difference between ends of stream

  33. Look for statistically significant break in constant stream drop property Break in slope versus contributing area relationship Physical basis in the form instability theory of Smith and Bretherton (1972), see Tarboton et al. 1992 Suggestion: Map channel networks from the DEM at the finest resolution consistent with observed channel network geomorphology ‘laws’.

  34. Statistical Analysis of Stream Drops

  35. T-Test for Difference in Mean Values 72 130 0 T-test checks whether difference in means is large (> 2) when compared to the spread of the data around the mean values

  36. Constant Support Area Threshold

  37. 200 grid cell constant support area based stream delineation

  38. Local Curvature Computation(Peuker and Douglas, 1975, Comput. Graphics Image Proc. 4:375) 43 48 48 51 51 56 41 47 47 54 54 58

  39. Contributing area of upwards curved grid cells only

  40. Upward Curved Contributing Area Threshold

  41. Curvature based stream delineation

  42. Channel network delineation, other options 4 3 2 1 1 1 1 1 1 1 1 1 1 5 6 7 1 1 1 4 2 3 2 2 3 1 1 Grid Order 8 1 1 1 2 1 1 1 1 3 12 1 1 1 1 1 1 2 1 16 3 1 2 1 1 2 3 6 2 25 3 Contributing Area

  43. Grid network pruned to order 4 stream delineation

  44. Slope area threshold (Montgomery and Dietrich, 1992).

  45. ? Topographic Slope Topographic Definition Drop/Distance Limitation imposed by 8 grid directions.

  46. The D Algorithm Tarboton, D. G., (1997), "A New Method for the Determination of Flow Directions and Contributing Areas in Grid Digital Elevation Models," Water Resources Research, 33(2): 309-319.) (http://www.engineering.usu.edu/cee/faculty/dtarb/dinf.pdf)

  47. Stream line Contour line Upslope contributing area a Specific catchment areaa is the upslope area per unit contour length [m2/m  m]

  48. Contributing Area using D Contributing Area using D8

  49. TOPMODEL Beven, K., R. Lamb, P. Quinn, R. Romanowicz and J. Freer, (1995), "TOPMODEL," Chapter 18 in Computer Models of Watershed Hydrology, Edited by V. P. Singh, Water Resources Publications, Highlands Ranch, Colorado, p.627-668. “TOPMODEL is not a hydrological modeling package. It is rather a set of conceptual tools that can be used to reproduce the hydrological behaviour of catchments in a distributed or semi-distributed way, in particular the dynamics of surface or subsurface contributing areas.”

  50. TOPMODEL and GIS Saturation in zones of convergent topography • Surface saturation and soil moisture deficits based on topography • Slope • Specific Catchment Area • Topographic Convergence • Partial contributing area concept • Saturation from below (Dunne) runoff generation mechanism

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